Steerable antenna

ABSTRACT

A telecommunication antenna comprising a reflector rests on foundations through a support assembly comprising a metal structure to which the reflector is fixed at the upper end, and a circular ring at the lower end. The ring rests on the foundations by means of rollers whose axes are horizontal and connected to the foundations. The ring rotates about the horizontal axis of the antenna by friction from drive rollers whose axes are vertical and supported by foundations.

United States Patent Foury Jan. 23, 1973 [541 STEERABLE ANTENNA 3,375,523 3/1968 Laibson ..343/766 3,604,011 9/1971 Hall ..343/766 [75 1 g Fury Le Hess Robmson 3,441,936 4/1969 Heine ..343/765 rance [73] Assignee: Compagnie Generale dAutm FOREIGN PATENTS OR APPLICATIONS time, Pans France 1,544,366 11/1967 France ..343/763 [22] Filed: Dec. 23, 1970 Primary Examiner-Eli Lieberman [21] Appl' 100344 Attorney-Sughrue, Rothwell, Mion, Zinn & Macpeak [30] Foreign Application Priority Data [57] ABSTRACT Dec. 23, 1969 France ..6944625 A telecommunication antenna comprising a reflector OCI. 23, 1970 France ..7038392 rests on foundations through a upport assembly comprising a metal structure to which the reflector is fixed [52] US. Cl ..343/766 at the upper end, and a circular ring at the km,er end. [51] Int. Cl. ..H0lq 3/00 The ring rests on the foundations by means of rollers [58] Field of Search ...343/763, 765, 766-, 912 whose axes are horizontal and connected to the foum dations. The ring rotates about the horizontal axis of [56] References cued the antenna by friction from drive rollers whose axes UNITED STATES PATENTS are vertical and supported by foundations.

2,599,381 6/1952 Cerks ..343/765 4 Claims, 5 Drawing Figures PATENTEU JAN 2 3 I975 SHEET l 0F 4 STEERABLE ANTENNA BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention concerns steerable antennas, and is more particularly concerned with an improved support arrangement for large steerable antennas.

2. Description of the Prior Art These antennas are generally orientable in any given direction by the combinations of rotation' about an azimuth or vertical axis and an elevation or horizontal axis. The accuracy of the orientation of the antenna in a given direction depends largely upon the stability of the azimuth axis. The antenna proper, generally comprising a reflector, is mounted on a rigid support structure resting on antenna foundations. Various proposals have already been made for realizing the cooperation between this rigid support structure and the antenna foundations.

In one proposal, an antenna reflector is slung between the arms of a bifurcate support whose stem is aligned with the azimuth axis of the antenna. If any displacement of the antenna foundations occurs, due to differential settling or seismic disturbances, for example, the azimuth axis may be displaced from the vertical. Jacks may be provided for re-aligning the azimuth axis by adjustment of the position of the stem. Such structures are generally very expensive. A less expensive proposal provides a wheel and track mounting. In this arrangement, a circular rail is mounted on the foundations of an antenna, the rigid support structure carrying wheels or rollers which run on the rail. The virtual azimuth axis is determined by the line passing perpendicularly through the center of the circle defined by the rail. While this arrangement is less expensive, it has a disadvantage in that, should the foundations be disturbed, it is not generally possible to realign the azimuth axis without dismantling and re-aligning the rail. While this disadvantage may be reduced by particular design of the antenna foundations, such measures tend to increase the overall cost. A lesser disadvantage is that such antennas are generally driven by a motor mounted on the rotating part, which may be inconvenient for the provision of an energy supply. Also, since the antenna may be stopped in any of its possible positions in the horizontal plane, the foundations must provide an equally strong support at all points on the circular rail.

SUMMARY OF THE INVENTION In accordance with the present invention, a steerable antenna comprises a rigid support structure rotatable on foundations about an azimuth axis of the antenna, the rigid support structure having a substantially horizontal annular first bearing surface resting on a set of support rollers fixed to the foundations.

The rigid support structure suitably has a second bearing surface in the form of a surface of revolution, guide rollers fixed to the foundations bearing against this second bearing surface to align the central axis of the first bearing surface with the azimuth axis of the antenna,

The invention will now be described in more detail, by way of examples only, with reference to the accompanying diagrammatic drawings in which:

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 and 2 are elevational views of two forms of steerable antenna.

FIG. 3 is a diagrammatic cross-section of a lower part of the antenna of FIG. 1.

FIG. 4 is a section on the line and in the direction of the arrows A-A in FIG. 3.

FIG. 5 is a partial section of a lower portion of the antenna of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, an antenna or aerial is mounted on foundations l0 and has a dish reflector 15. The reflector 15 is mounted on a rigid support structure indicated generally at 16 and consisting of a metal girder construction 17 supporting a mounting providing rotation of the reflector 15 about a horizontal elevation axis 18. A hollow body in the form of a cylindrical metal structure 19 is attached to the bottom of the girder construction 17. A lower face of the structure 19 defines a substantially horizontal annular first bearing surface 20 resting on a set of support rollers fixed to the foundations 10 and diagrammatically indicated at 30.

The antenna is steerable about its azimuth axis, coincident with the central axis of the cylinder 19. It is orientable in any given direction by the combination of rotations about this azimuth axis and the horizontal axis 18.

The foundations 10 are constructed as a cabin for ancillary equipment of the aerial and its operating staff.

Referring to FIG. 2, a second form of antenna is generally similar to that of FIG. 1, and those elements bearing the same reference numerals fulfill analogous functions. The cylinder 19 of FIG. 1 is replaced by an upper cabin structure indicated generally at 19 in FIG. 2. This consists essentially of a frusto-conical concrete shell 51, the girder construction 17 being attached to this at its upper end, as will be further explained below. Fastened to the lower face of the skirt 51 is a circular flat rail 52 providing the annular support surface against which bear the support rollers 30, in this case mounted in pairs or bogies on the foundations 10. A lower cabin 53 is situated between the support rollers 30 and below the upper cabin 19. The position of each set of rollers 30 is adjustable by means of a jack indicated diagrammatically at 55, allowing adjustments of the azimuth axis of the antenna.

An elevator shaft 12 extends upwardly from the cabin 53, carrying an elevator giving personnel access to the antenna proper, a ladder for use when the elevator may not be used, and various of the connections to the aerial proper.

Referring now to FIG. 3, the girder construction 17 is mounted on the cylinder 19 by means of a chassis plate 8. As is seen in FIG. 4, this chassis plate 8 is rectangular and is attached to the cylinder 19 by triangular intermediate elements such as 9, only two of which have been shown in the drawings for the sake of simplicity.

The cross-section of the cylinder 19 has the form of an I-beam with a web 21 and respective upper and lower transverse flanges 22 and 23. The lower face 20 of the lower flange 23 defines the annular first bearing surface, which rests on a set of support rollers, one of which is indicated at 30. From FIG. 4, it is seen that the cylinder 19 is supported on six equally spaced rollers 30. The number of such support rollers will depend mostly on the weight of the aerial structure.

The axis 31 of each roller 30 is substantially horizontal, these rollers being attached to the foundations by any suitable known arrangement.

An arrangement (not shown) of jacks or the like enables the position and the inclination of the axis of each roller to be adjusted, so that it is possible to ensure that the azimuth axis of the antenna is exactly vertical. Should the verticality of this axis become disturbed, for example due to differential settling of the foundations or seismic disturbances, the azimuth axis can be realigned by appropriate actuation of this arrangement.

While in this particular antenna the annular face 20 is substantially horizontal, and the roller axes 31 are also substantially horizontal, in some applications it may be possible and advantageous to arrange that the axes 31 converge at a point on the aximuth axis below the rollers themselves. The lower flange 23 would then be made slightly frusto-conical, the interengagement of the frusto-conical flange and the frusto-conical, arrangement of the rollers providing an automatic centering of the azimuth axis. This axis has been shown in FIGS. 3 and 4 by the line 50.

In the antenna under discussion, centering of the azimuth axis 50 is achieved by a set of three guide rollers, equi-angularly spaced around the axis 50, two of these rollers being shown at 40 and 45 respectively. A portion of the internal surface of the cylinder 19 defines a second bearing surface against which the guide rollers 40, 45 bear.

The guide roller 40 is motor-driven to provide a steering drive for the antenna. It is driven by a motor and gearing arrangement 41, an idler roller 42 being provided outside the cylinder 19 and opposite the driven roller 40. The rollers 40 and 42 have solid or pneumatic tires, that of roller 40 being shown at 43, and tightly grip the cylinder 19 to provide a drive without slip. The roller tires serve to absorb the slight shocks undergone upon starting and stopping rotation of the antenna.

Thelmotor assembly 41 may be placed inside the cylinder 19, so being protected from inclement weather conditions. Furthermore, since it does not move, supply connection is simple.

As well as centering the antenna and properly aligning its azimuth axis, it is necessary to resist overturning movements, due for example to high winds, tending to topple the antenna. This is achieved by associating with each support roller 30 a pair of retaining rollers 35, 36 bearing against upper surfaces of the flange 23. Each of these. flange upper faces defines an annular bearing surface against which the retaining rollers bear.

As is seen in FIG. 3, the rollers35, 36 are carried in the same mount as the rollers 30.

As well as resisting tilting of the antenna, these retaining rollers prevent its moving upwardly. It is thus whereas many types of antenna previously proposed must be shut down and temporarily fastened in position until conditions improve.

Evidently, this retaining of the antenna in a vertical sense could be obtained with a single roller, instead of a pair, preferably located inside the cylinder for protection against adverse weather conditions. Likewise, it is not necessary for this roller to bear against the upper surface of the flange 23. It is equally possible for a special track for the retaining rollers to be provided inside the cylinder, or even outside it.

Since the motor-driven roller 40 has no support function, it may be of smaller diameter than is the case in previously proposed arrangements. Consequently, the

amount of speed reduction required between the motor 41 and the rotor 40 is reduced. A clutch arrangement may be provided for the driven roller 40. As for the support rollers 30 since a large number of these may be provided their diameter may be reduced.

If the guide rollers 40, 45 are displaceable along horizontal lines radiating from the axis 50 and passing through their centers, a regulation of the position of the azimuth axis 50 in the horizontal plane is possible. With such an arrangement (not shown in the drawings) movements of the azimuth axis 50 of the order of a few centimeters are obtainable.

Referring now to FIG. 5, the mounting of the antenna of FIG. 2 is shown in more detail. Those portions of FIG. 5 which are shown in FIG. 2 will not be described again; they carry the same reference numerals as in FIG. 2.

The rail 52 may suitably be incorporated in the skirt 51 during the casting of the latter. The rail 52 rests on the support rollers 30, at least one of which will be motor-driven to provide a steering drive for the anten- Internally, the skirt 5] has an integral floor providing the floor of the upper cabin 19. Below this floor, an inwardly facing projection 58 has an inclined face 50 defining a second bearing surface, having the form of a surface of revolution. Guide rollers 57, flxed to the foundations l0, and having inclined axes lying parallel to the face 50, bear against this second bearing surface to align the central axis of the first bearing surface 20 with the azimuth axis of the antenna. At the same time, since the surface 50 is inclined, these rollers 57 serve the purpose of the retaining rollers 35, 36 of FIG. 3.

While the guide-retaining rollers 57 are shown adjacent the support roller 30 in FIG. 5, it will be appreciated that these two rollers may be separated, the roller 57 being circumfercntially located between the successive rollers 30. The rollers 57 may be provided with solid or pneumatic tires, providing a certain amount of resilience in the antenna location. They may be complemented by further guide rollers (not shown) with vertical axes bearing against the vertical inside face of the projection 58.

The metal girder construction 17 of the antenna is fastened to the skirt 51 by attaching the pre-stressing cables 56 at their upper extremities to the construction 17.

-An advantage of the antenna structure just described is that the strength required in the foundations may be localized. In the conventional wheel and track system, where the rail is fixed and the rotating part of the antenna carries the wheels or rollers, an equally strong support must be provided at every point along the rail. In these new arrangements, however, the load imposed by the weight of the antenna always passes through the fixed support rollers 30. Thus it may be possible in some applications for the foundations to consist simply of a number of pillars equal to the number of support rollers 30, each pillar holding one of these rollers.

These foundation pillars, or more generally the strongest parts of the foundation, define a support polygon which will be only slightly larger than the cylindrical portion 19 of the rigid support structure of the antenna. The provision of the retaining rollers 35, 36 or 57 means that a much smaller base may be used for the antenna than is the case in arrangements where provision against tilting depends only on gravity, necessitating a relatively large base.

What is claimed is:

1. A steerable antenna comprising:

a rigid antenna support structure,

means rotatably mounting said support structure on foundation means about an azimuth axis of the antenna,

a set of support rollers fixed to the foundation means,

said rigid support structure having a substantially horizontal annular first bearing surface resting thereon, said rigid support structure including a second bearing surface in the form of a surface of revolution,

guide rollers fixed to the foundation means and bearing against said second bearing surface to align the central axis of the first bearing surface in the azimuth axis of the antenna,

said rigid support structure including a hollow body carrying on a lower face a circular rail which defines the first bearing surface and wherein a portion of the internal surface of said body defines said second bearing surface, and wherein said hollow body is frusto-conical and has on an inside surface an inwardly facing flange, one face of which defines said second bearing surface.

2. The antenna as claimed in claim 1, wherein at least one of the guide rollers is motor-driven to provide an antenna steering drive.

3. A steerable antenna comprising:

a rigid antenna support structure,

means rotatably mounting said support structure on foundation means about an azimuth axis of the antenna,

a set of support rollers fixed to said foundation means,

said rigid support structure including a hollow body carrying on a lower face a circular rail which defines a first bearing surface of substantially horizontal annular form upon which rests said set of support rollers,

a portion of the internal surface of said body defining a second bearing surface in the form of a surface of revolution,

guide rollers fixed to the foundation means and bearing against the second bearing surface to align the central axis of the first bearing surface with the azimuth axis of the antenna,

said hollow body comprising a cylindrical metal element having at its lower end a horizontal flange whose lower face defines the first bearing surface and an upper face which defines an annular third bearing surface and said antenna further includes retainer rollers fixed to the foundation means and bearing against said third bearing surface.

4. The antenna as claimed in claim 3, wherein at least one of the guide rollers is motor-driven to provide an antenna steering drive. 

1. A steerable antenna comprising: a rigid antenna support structure, means rotatably mounting said support structure on foundation means about an azimuth axis of the antenna, a set of support rollers fixed to the foundation means, said rigid support structure having a substantially horizontal annular first bearing surface resting thereon, said rigid support structure including a second bearing surface in the form of a surface of revolution, guide rollers fixed to the foundation means and bearing against said second bearing surface to align the central axis of the first bearing surface in the azimuth axis of the antenna, said rigid support structure including a hollow body carrying on a lower face a circular rail which defines the first bearing surface and wherein a portion of the internal surface of said body defines said second bearing surface, and wherein said hollow body is frusto-conical and has on an inside surface an inwardly facing flange, one face of which defines said second bearing surface.
 2. The antenna as claimed in Claim 1, wherein at least one of the guide rollers is motor-driven to provide an antenna steering drive.
 3. A steerable antenna comprising: a rigid antenna support structure, means rotatably mounting said support structure on foundation means about an azimuth axis of the antenna, a set of support rollers fixed to said foundation means, said rigid support structure including a hollow body carrying on a lower face a circular rail which defines a first bearing surface of substantially horizontal annular form upon which rests said set of support rollers, a portion of the internal surface of said body defining a second bearing surface in the form of a surface of revolution, guide rollers fixed to the foundation means and bearing against the second bearing surface to align the central axis of the first bearing surface with the azimuth axis of the antenna, said hollow body comprising a cylindrical metal element having at its lower end a horizontal flange whose lower face defines the first bearing surface and an upper face which defines an annular third bearing surface and said antenna further includes retainer rollers fixed to the foundation means and bearing against said third bearing surface.
 4. The antenna as claimed in claim 3, wherein at least one of the guide rollers is motor-driven to provide an antenna steering drive. 